Different views about the biomechanics of the knee joint and late re construction of ligamentous injuries underline the obstacles impeding the establishment of generally acceptable principles for the treat ment of such lesions. As late as June 1976, HUGHSTON emphasized in the Journal of Bone and Joint Surgery that in spite of excellent anatomic studies, substantial uncertainty still prevails in knee joint surgery. Even the signifi cance of the anterior drawer sign for ruptures of the anterior cru ciate ligament is interpreted quite diversely, as illustrated in a comparison of HUGHSTON, GIRGIS, TORG, and SCHIECK, who give varying opinions concerning the indication related to the age of the patient or possible earlier joint damage as well as concerning the prognosis for untreated knee joints. The question still remains as to how often an intra-articular ligamentous replacement should be carried out in addition to extra-articular techniques (0 'DONOGHUE, SLOCUM, NICHOLAS, HUGHSTON). Lastly the question of synthetic ligament replacement must be clarified. After basic research has well advanced, clinical ex perience must be discussed. Statements concerning the therapeutic value of diverse procedures based solely on knowledge of the literature remain problematic. For this reason a workshop was held at the University of Heidelberg in the Orthopedic Clinic (Head: Prof. Dr. H. COTTA) in June 1977, with the aim of bringing together representatives of the different leading schools in a round table discussion to comment on still unsolved ques tions."

Photodynamic therapy (PDT) is increasingly being used amongst health practitioners in combating a variety of diseases. One common strategy used during this light activated process is to induce the accumulation of significant amounts of a photosensitising agent in the diseased tissue. The naturally occurring amino acid 5-aminovulinic acid (ALA) is used to produce high levels of the photosensitizer, Protoprophyin IX, in the therapy known as ALA-PDT. Written by experts in the field Photodynamic therapy with ALA outlines a variety of clinical approaches to the topic, outlining current applications. These include the use of ALA-PDT and ALA-FD (fluorescence diagnosis) in the areas of dermatology, urology, brain, otorhinolaryngology, gynaecology and gastroenterology. Also included is a chapter that comprehensively reviews the scientific principles of ALA-PDT. Primarily aimed at a clinical audience Photodynamic therapy with ALA should provide a comprehensive review and useful insight into ALA-PDT.